Chassis Suspension

ABSTRACT

A chassis suspension ( 10 ) for rail vehicles ( 36 ), the chassis suspension including a carriage body ( 12 ) which is supported on a chassis ( 16 ) via a spring system ( 18 ), the chassis suspension ( 10 ) having an anti-lift device ( 24 ) with a stop element ( 30 ) fixed in respect to the carriage body ( 12 ) and a stop element ( 28 ) fixed in respect to the chassis ( 16 ), between which stop elements free play exists which limits the rebound travel of the spring system ( 18 ) if the carriage body ( 12 ) is raised, and a level adjustment device for the carriage body ( 12 ) is formed by an extendable actuator ( 34 ) positioned between the two stop elements ( 28, 30 ).

The invention relates to a chassis suspension for rail vehicles, the chassis suspension comprising a carriage body which is supported on a chassis via a spring system, the chassis suspension having an anti-lift device with a stop element fixed in respect to the carriage body and a stop element fixed in respect to the chassis, between which stop elements free play exists which limits the rebound travel of the spring system if the carriage body is raised.

Such an anti-lift device makes is possible to lift the entire rail vehicle off the rail by means of a lifting gear that is attached to the carriage body, without overstretching the elastic elements of the spring system. In known chassis suspensions, the stop element that is fixed in respect to the chassis is formed for example by a bracket that projects upwards from the chassis, whereas the stop element that is fixed in respect to the carriage body is formed at the lower end of a bolt that projects downwardly from the carriage body and passes through and is axially movable in a bore formed in the base of the bracket. Thus, the stop element at the lower end of the bolt is located below the base of the bracket that forms the stop element of this chassis. When the carriage body is lifted and the springs of the spring system rebound, the bolt moves upwards in the bore of the bracket until the stop element at the lower end of the bolt abuts at the base of the bracket and thereby limits the rebound travel. When the carriage body continues to be lifted, the chassis that is suspended on the anti-lift device is lifted together with the carriage body.

In view of a barrier-free design of passenger transport systems it is desired for rail vehicles that the level difference between the platform and the entrance of the rail vehicle can be limited to maximally 50 mm, regardless of the load. To that end, level adjustment devices have been known with which the carriage body can hydraulically be drawn towards the chassis against the force of the spring system, so that, when the load of the rail vehicle is low, the entrance level can be reduced. An example of such a level adjustment device has been described in DE 20 2015 101 275 U1.

However, the known level adjustment devices require some installation space in the chassis suspension, whereby it is difficult to retrofit existing rail vehicles with a level adjustment device.

It is an object of the invention to provide a chassis suspension in which a level adjustment device can be accommodated in a compact manner.

According to the invention, in order to achieve this object, a level adjustment device for the carriage body is formed by an extendable actuator positioned between the two stop elements.

Thus, according to the invention, the stop elements of the anti-lift device, that are present anyway, are utilized for the level adjustment device. When the entrance level of the carriage body is to be reduced, the actuator is extended so that a backlash between the stop elements is bridged and then, when the rebound travel continues, the stop element on the side of the carriage body is pressed downwards against the force of the spring system while the actuator is supported at the stop element on the side of the chassis. In this way, the installation space for the level adjustment device is primarily provided by the space that is needed anyway for the stop elements of the anti-lift device and the backlash existing between them. This permits a low-cost design of the level adjustment device and, in particular, a simple retrofit of existing vehicles.

Useful details of the invention are indicated in the dependent claims.

An embodiment example will now be described in conjunction with the drawings, wherein:

FIG. 1 is a design sketch of essential parts of a chassis suspension of a rail vehicle;

FIG. 2 is a total view of the rail vehicle:

FIG. 3 is a sketch analogous to FIG. 1, illustrating the function of an anti-lift device; and

FIG. 4 is an illustration analogous to FIGS. 1 and 3 showing the function of a level adjustment device.

The chassis suspension 10 shown in FIG. 1 serves for mechanically connecting a carriage body 12, of which only a part of a bottom wall 14 has been shown here, to a chassis 16 of a rail vehicle. For sprung support of the carriage 12 on the chassis 16, a spring system 18 is provided which is formed in this example by two helical spring packages 20 which are each supported on the carriage body 16 with their lower end and on the top ends of which the carriage body 12 is supported via counter-bearings which have not been shown here.

In addition, the carriage body 12 and the chassis 16 are interconnected by an oscillation damper 22 that acts in parallel with the spring system 18 and dampens oscillations of the latter. On the opposite side of the spring system 18, symmetrically with respect to the oscillation damper 22, an anti-lift device 24 is provided which serves for limiting the rebound travel of the spring system 18 when the carriage body 12 is lifted.

A part of the anti-lift device 24 is formed by a bracket 26 in the form of an inverted U which projects from the chassis 16 and the base of which forms a first stop element 28 that is fixed in respect to the chassis. Another stop element 30, that is fixed in respect to the carriage body, is formed at the lower end of a bolt 32 which passes through a bore of the first stop element 28 and is suspended in an articulated manner at the bottom side of the carriage body 12.

An extendable actuator 34 that is formed for example by a hydraulic cylinder and an associated piston is arranged between the two stop elements 28 and 30. The bolt 32 passes coaxially through the actuator 34 and is sealed such that no hydraulic fluid can leak out.

The installation of the chassis suspension 10 shall now be explained by reference to FIG. 2 which is a total view of a rail vehicle 36. In the example shown, the rail vehicle 36 is a five-section vehicle having three carriage modules 38, 40, 42 with a sedan 44, 46 held between each pair of carriage modules.

Each of the three carriage modules 38, 40, 42 has a chassis 16 that is connected to the carriage body 12 of the respective carriage module by two corresponding chassis suspensions 10 of the type shown in FIG. 1. The two chassis suspensions 10 per carriage module are arranged on opposite sides of the vehicle such that their oscillation dampers 22 and anti-lift devices 24 are respectively arranged diagonally opposite to one another.

The diagonal arrangement of the anti-lift devices 24 permits to stably lift the chassis 16 when the carriage body 12 is lifted by means of a lifting gear.

The function of the anti-lift device 24 has been illustrated in FIG. 3 which shows the carriage body 12 and the bottom wall 14 thereof in a lifted position. For comparison, the initial position has been indicated in phantom lines in FIG. 3.

The stop element 30 provided at the bottom end of the bolt 32 has been lifted together with the carriage body and the bolt 32 and now engages the bottom side of the actuator 34 which continues to be supported by the stop element 28 at its top end. When, now, the carriage body 12 is lifted further, the chassis 16 is lifted together with it, with the train of force passing from the carriage body via the bolt 32, the stop element 30, the actuator 34 and the stop element 28 to the bracket 26.

The actuator 34 is connected to a controller, which has not been shown, via hydraulic lines that have not been shown, neither, the controller being provided for controlling the extension movement and the retraction movements, as the case may be, of the actuator 34.

When the carriage body 12 shall be lowered at a station in order for the entry of the rail vehicle to be level with the platform, the controller receives the command to extend the actuator 34 into the position shown in FIG. 4. Thereby, the backlash that normally exists between the stop elements 28 and 30 is bridged, and when the actuator 34 is extended further, the stop element 30 is forced downwards, so that the carriage body 12 is also drawn downwards via the bolt 32, as has been shown in FIG. 4. For comparison, the initial position of the carriage body, as in FIG. 1, has again been shown in phantom lines.

The actuators 34 of the two diagonal opposite anti-lift devices 24 in the two chassis suspensions 10 are controlled synchronously, so that the entire carriage body is lowered stably and its horizontal posture is maintained. If, for example the sedan 44 is to be lowered, the carriage bodies 12 of the two adjacent carriage modules 38 and 40 are lowered in this way, whereby the sedan 44 held between these carriage bodies is also lowered evenly, whereas the other sedan 46 is slightly tilted, unless the carriage body of the carriage module 42 is lowered as well.

In principle, the actuators 34 may be single-action hydraulic cylinders. The retraction movement is then driven by the weight of the carriage body. In an advantageous embodiment, however, the actuators 34 are formed by double-action hydraulic cylinders, so that the backlash between the stop elements 28 and 30, as shown in FIG. 1, can be restored actively.

The controller for the actuators 34 can optionally be coupled with the brake system of the rail vehicle such that, during a stop of the rail vehicle and actuation of the brake, all sedans are lowered evenly. However, the controller may also be arranged to operate independently of the brake system. For example, request keys may be provided at the doors of the rail vehicle (in the sedans 44, 46), via which the passengers may request a lowering of the corresponding sedan, if required, with the result, that the carriage bodies 12 of the two adjacent carriage modules are lowered. 

What is claimed is:
 1. A chassis suspension for rail vehicles, comprising: a spring system for supporting a carriage body on a chassis, an anti-lift device including: a stop element fixed in respect to the carriage body, a stop element fixed in respect to the chassis, between which stop elements free play exists which limits rebound travel of the spring system if the carriage body is raised, and a level adjustment device for the carriage body formed by an extendable actuator positioned between the two stop elements.
 2. The carriage suspension according to claim 1, wherein: the stop element that is fixed in respect to the chassis is formed by a base of a bracket that projects upwardly from the chassis, and the stop element that is fixed in respect to the carriage body is formed at the lower end of a bolt that extends downwardly from the carriage body and passes through a bore of the stop element formed at the bracket.
 3. The chassis suspension according to claim 2, wherein the actuator is a hydraulic cylinder.
 4. The chassis suspension according to claim 2, wherein the bolt passes coaxially through the actuator and is axially moveable relative thereto.
 5. The chassis suspension according to claim 1, further including an oscillation damper connected between the chassis and the carriage body, and wherein the anti-lift device and the oscillation damper are symmetrically arranged on opposite sides of the spring system.
 6. The chassis suspension according to claim 5, comprising two assemblies which are arranged on opposite sides of the rail vehicle and each comprise said spring system, said oscillation damper and said anti-lift device, wherein the two anti-lift devices and the two oscillation dampers are arranged such that they are respectively arranged diagonally opposite to one another. 